Manufacturing methods of organic EL display panel are broadly classified into two types according to the method with which their organic functional layer is formed: The first one is to form organic functional layers by vapor deposition, and the second one is to form them by solvent coating.
One representative method of the formation of organic functional layers by solvent coating involves the use of an inkjet device for discharging ink droplets, which contain organic functional material, onto a display substrate to form thereon organic functional layers (see e.g., Patent Document 1).
The organic material-containing ink is applied on luminescent regions provided on the display substrate. As used herein, the term “luminescent region” means a region in which red (R), green (G) or blue (B) sub pixels are aligned in a row. Namely, the display panel includes sets of three different color luminescent regions (red, green and blue), which are arranged side by side in a specific direction and run in parallel to one another.
The luminescent regions may be further partitioned into sub pixels by banks or may remain as linear regions without being partitioned. In the case of partitioning the luminescent regions into sub pixels by banks, the banks define regions for the sub pixels. An ink containing organic functional material is then supplied on a sub pixel basis (see e.g., Patent Documents 2-5).
By contrast, when the luminescent regions are not partitioned into sub pixels by banks (i.e., when the luminescent regions are linear), the banks define the luminescent regions. An ink containing organic functional material is then applied on a luminescent region basis (see e.g., Patent Documents 6-10).
It has been recognized that the size of ink droplets discharged from an inkjet head varies from one nozzle to another (see e.g., Patent Document 11).
Moreover, methods of equalizing the drying rates of the applied organic functional material-containing ink have been suggested in which multiple sets of sub pixels are surrounded by banks and regions defined by the banks are staggered (see e.g., Patent Document 12).    Patent Document 1: Japanese Patent Application Laid-Open No. 2004-362818    Patent Document 2: Japanese Patent Application Laid-Open No. 2004-87509    Patent Document 3: Published U.S. Patent Application No. 2002/0097363    Patent Document 4: Published U.S. Patent Application No. 2002/0008311    Patent Document 5: Published U.S. Patent Application No. 2004/0021413    Patent Document 6: U.S. Pat. No. 7,091,660    Patent Document 7: Japanese Patent Application Laid-Open No. 2007-227127    Patent Document 8: Japanese Patent Application Laid-Open No. 2004-288403    Patent Document 9: Published U.S. Patent Application No. 2002/0041150    Patent Document 10: Published U.S. Patent Application No. 2007/0138943    Patent Document 11: Japanese Patent Application Laid-Open No. 2003-266669    Patent Document 12: Japanese Patent Application Laid-Open No. 2007-115563